1. Field of the Invention
The invention relates to a display substrate and a method for manufacturing the display substrate. More particularly, the invention relates to a display substrate including an oxide semiconductor thin-film transistor (“TFT”) and a method for manufacturing the display substrate.
2. Description of the Related Art
Generally, a display device includes an array substrate including a switching element, and a counter substrate opposite to the array substrate. The switching element includes a gate electrode connected to a gate line, a semiconductor pattern insulated from the gate electrode, a source electrode connected to a date line and electrically connected to the semiconductor pattern, and a drain electrode spaced apart from the source electrode.
A TFT used as the switching element of the display device includes an amorphous-silicon TFT (“amorphous-Si TFT”), a poly-silicon TFT (“poly-Si TFT”), an oxide semiconductor TFT and so on.
The amorphous-Si TFT may be uniformly formed on a large substrate at a low cost, but a mobility of an electric charge is low. The poly-Si TFT has a higher mobility of an electric charge than the amorphous-Si TFT, and a deterioration of a characteristic of the poly-Si TFT is small, but a manufacturing process of the poly-Si TFT is complicated so that a cost for manufacturing is high.
The oxide semiconductor TFT may use a low temperature process, have a higher mobility of an electric charge and be easy to form a large area. However, an oxide semiconductor may react with a source electrode or a drain electrode which includes a metal. Thus, a positive ion included in the oxide semiconductor is deoxidized and extracted to cause a defect.
When the positive ion included in the oxide semiconductor is deoxidized and extracted, a composition of a channel layer of the TFT is changed so that the mobility of the electric charge may be decreased. In addition, a resistance of a wiring may be increased by a metal extracted from the oxide semiconductor. Thus, electrical safety and reliability of the switching element may be decreased.